The overload interruption structures equipped with a power switch device known to applicant are disclosed in U.S. Pat. Nos. 5,786,742, 5,223,813, 4,937,548, 4,661,667, 4,931,762, 5,451,729 and 4,704,594. In U.S. Pat. No. 4,937,548, a thermally deformed bimetal plate is operationally connected to a cam to open the circuit. However, the action to open the circuit takes time because the cam is indirectly operated by the bimetal plate so that there is a possibility that the electric current will destroy the electric equipment when the current is overload. Furthermore, an additional wire is required to connect between the bimetal plate and a conductive plate. In U.S. Pat. No. 5,786,742, the switch is directly connected to the conduct point so that the open action for the circuit is not fast enough to timely protect the equipment.
The present invention intends to provide a power switch device that has a simple structure and timely open the circuit to protect the electric equipment.